1. Field of the Invention
This invention pertains to an inside collet for coaxial placement of a diode. More particularly, this invention pertains to a collet assembly for precisely positioning an electronic device axially along a cylindrical bore in coaxial relation thereto and in electrical and thermal connection with an element through which the bore extends.
2. Description of the Prior Art
IMPATT diodes are well known for their use in microwave oscillators. Each such diode, typically, is of a cylindrical configuration with one end being one terminal of the diode and the opposite end portion being externally screw threaded. A flange circumscribes the diode between such end and such end portion, and the flange and the end portion serve as the other terminal of the diode. When so used, the diode is, typically, disposed coaxially in a cylindrical bore having a transformer, which is a cylindrical slug disposed coaxially in the bore, insulated electrically therefrom, and presenting an axial end surface through which electrical connection is made to the one terminal of the diode. The diode, for test purposes, may be used individually with transformers of various axial lengths so that it is necessary to vary the axial position of the diode in the bore. As the diode position varies, the one terminal must remain effectively connected electrically to the transformer while the other terminal remains effectively connected to an element providing the bore both electrically and thermally for dissipation of heat from the diode.
Prior art arrangements for so mounting an IMPATT diode have included shims, which are inconvenient since they must be changed for use with different transformers and only position the diode at predetermined positions, and springs, which are received coaxially in the bore and which result in poor electrical contact since the small diameter of the bore of, typically about 1/8 inch (3 mm), does not permit the use of springs exerting sufficient force. Other prior art arrangements have included collars disposed in circumscribing relation to the diode and screw threads within the bore in the immediate vicinity of the diode. Such collars require that the diodes in arrays thereof be spaced radially substantial distances apart. Such spacing is highly undesirable when an array of diodes is used to obtain greater microwave power output than one diode can provide and when the array must be compact. It is highly undesirable that the bore have irregular surfaces, such as screw threads, in the vicinity of the diode since such surfaces produce unwanted reflections of microwaves within the bore. It is, in any event, difficult to provide satisfactory electrical connection by contact between screw threads.